<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .a{
            color:aqua
        }
    </style>
    <script>
          console.log(2); 
        console.log(1);
        var value = 21290341;
        new Array(2);
        Array.isArray(value);
        console.log(typeof value);
        console.log(3); 
        console.log(2); 
        console.log(1);
        document.getElementById('a');
        document.body;//获得body标签
        document.documentElement;//获得html标签
        document.getElementsByClassName("a");
        document.getElementsByTagName("li");
        document.querySelector("#a");//可以通过参数来进行改变我们说选择的标签
        document.querySelectAll('.aa');
    </script>
</head>
<body>
    <p class="a"></p>
</body>
</html>